The present invention relates to digital rights management. In particular, this invention relates to user-based rights management independent of format.
Digital content providers often wish to limit the distribution of the content they provide. In some instances, these limitations may help to preserve the value of the content by restricting the distribution of unlicensed copies. In other cases, these limitations can prevent the widespread distribution of proprietary materials, such as software programs developed for use within a particular company.
Digital content is often available in a variety of formats. For example, music files can be provided in MP3, WAV, Windows Media Audio, RealAudio, Vorbis, Advanced Audio Coding (AAC), or other formats. Similarly, ring tones and screen savers are available in different formats for different mobile telephones. As a result, a single song could be available in a variety of formats. In some cases, different media players such as personal computers, portable MP3 players, and car audio systems may support only some of those formats. This can pose difficulties to an individual intent on listening to digital music. He may, for example, download a song as a Windows Media Audio (WMA) file for use on a personal computer. If his portable MP3 player cannot decode WMA files, however, he cannot listen to that song on his MP3 player until he obtains a copy of the song in the MP3 format.
Even where there is a single file format that can be decoded by all of an individual's media players, it may be preferable to use different formats on different players. For example, MP3 files may be readable to all of the user's media players. The MP3 format, however, does not offer lossless compression. If the user has one device that can read a file format that uses lossless compression, he may prefer such files on that device.
These difficulties can be overcome in many instances. In the case of music files in the public domain, for example, the user may simply download the content in as many different formats as he needs. If he has appropriate software, he can transfer a file into different formats. These steps are little more than an inconvenience. If, on the other hand, the content is not in the public domain, the user may be required, whether by the terms of a license or by digital rights management software, to purchase multiple copies of the same content in different file formats.
A user encounters a similar difficulty if content he has purchased is later released in a more technically advanced file format. If he wishes to enjoy the content in the more advanced format (which may, for example have better sound quality, smaller file size, or other advantageous features), he is forced to purchase the content in the new format.